Heat insulating structure for hot air blower

ABSTRACT

A heat insulating structure for hot air blower mounted between the inner barrel and the our cover thereof is provided for protecting users from being burned due to overheating of the outer cover. It is featured by a heat insulating member sandwiched by the inner wall of the outer cover and a flange on the outer wall of the inner barrel. The heat insulating member stops heat from being conducted toward the outer cover and thus achieves effects of enhancing user&#39;s safety and protecting the outer cover from burning out.

FIELD OF INVENTION

The present invention relates to safety mechanisms of a hot air blower, and more particularly to a heat insulating structure for hot air blower including a heat insulating member locked between a inner barrel and the outer cover of a hot air blowers for preventing heat from being conducted toward the outer cover.

DESCRIPTION OF THE PRIOR ART

A conventional hot air blower for industrial use comprises a fan motor assembly, an inner barrel, a heating element, a nozzle and an outer cover. The fan motor assembly drives airflow to pass through the inner barrel, the airflow being heated by the heating element and ejected from the nozzle. Since the working temperature in the inner barrel is approximately 500-600 hundred degrees Celsius, the inner barrel is usually made of metals, which will conduct heat efficiently to the outer cover. After a time period of operation, the outer cover will be so hot so that it becomes hazardous to people who touches it. Also, the heat accumulated on the inner wall of the outer cover due to conduction will also damage the inner wall.

As shown in FIG. 1, a hot air blower 1 according to U.S. Pat. No. 6,370,326 to Cheng includes a nozzle 13 connected to the front end of an inner barrel 11. An outwardly extending flange 131 disposed at the rear end of the nozzle 13 is provided with a plurality of radially arranged through holes 132. The flange 131 supports against the inner wall of the outer cover of the hot air blower 1, so as to insulate the outer cover from the hot nozzle 13. A fan motor assembly 12 mounted at the rear end of the inner barrel 11 drives airflow through the inner barrel 11, mainly passing through the nozzle 13 with a minor portion passing through the through holes 132 for cooling the flange 131. As shown in FIG. 2, a hot air blower 1 according to U.S. Pat. No. 6,460,272 to Cheng includes a positioning ring 22 around an inner barrel 21. The positioning ring 22 is provided with a plurality of support pieces cast on the inner wall thereof for defining a gap between the positioning ring 22 and the inner barrel 21. A fan motor assembly 24 drives airflow through the inner barrel 21 as well as the gap between the positioning ring 22 and the inner barrel 21, thereby cooling the positioning ring 22.

The aforecited inventions provides a cooling mechanism that prevents efficient heat conduction from the interior heated parts of a hot air blower to its outer cover. However, it is discovered that the conventional mechanism cannot prevent the outer cover of a hot air blower from overheating under longtime operation. Therefore, a more efficient mechanism that insulates the heat produced in the inner barrel is necessary.

SUMMARY OF THE INVENTION

Accordingly, the primary object of the present invention is to provide a heat insulating structure for hot air blower wherein a heat insulating member sandwiched by the inner wall of the outer cover and a flange on the outer wall of the inner barrel. The heat insulating member stops heat from being conducted toward the outer cover and thus achieves effects of enhancing user's safety and protecting the outer cover from burning out.

The secondary object of the present invention is to provide a heat insulating structure for hot air blower wherein the heat insulating member encloses the outer rim of the flange and is embedded in an annular groove around the inner wall of the outer cover, so that airflow between the inner barrel and the outer cover passes through the holes on the flange only. Furthermore, since the heat insulating member has a low heat expansion coefficient, it provides a better positioning effect for the inner barrel.

The various objects and advantages of the present invention will be more readily understood from the following detailed description of preferred embodiments, when read in conjunction with the appended drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of the invention disclosed in one prior art.

FIG. 2 is a perspective view of the invention disclosed in another prior art.

FIG. 3 is an exploded perspective view of the first preferred embodiment according to the present invention.

FIG. 4 is a perspective view showing the combination of the flange and the heat insulating member in the first preferred embodiment.

FIG. 5 is a cross-sectional view of the first preferred embodiment.

FIG. 6 is an exploded perspective view of the second preferred embodiment according to the present invention.

FIG. 7 is a cross-sectional view of the second preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 3 and 5, a heat insulating structure for hot air blower according to the present invention comprises an inner barrel 30, an outer cover 34, a tapered nozzle 31 and a heat insulating member 33. The inner barrel 30 contains a high-impedance resistance heating element therein, which is not shown in the figures. The tapered nozzle 31 includes a positioning flange 32 extending outwardly from a rear end thereof. The rear end of the nozzle 31 is connected to the front end of the inner barrel 30. The flange 32 is further provided with a plurality of circularly arranged through holes 321 for passing cooling airflow. The outer cover 34 is provided with a substantially annular groove 341 molded on an inner wall thereof. The heat insulating member 33, being substantially annular, is sandwiched by the flange 32 and the outer cover 34, the inner rim of heat insulating member 33 enclosing the outer rim of the flange 32, and outer rim of the heat insulating member 33 being embedded in annular groove 341. The heat insulating member 33, secured between the inner barrel 30 and the outer cover 34, therefore stops heat generated inside from being conducted toward the outer cover 34 and achieves effects of enhancing user's safety and protecting the outer cover from burning out.

Referring to FIGS. 6 and 7, another preferred embodiment of a heat insulating structure for hot air blower according to the present invention comprises an inner barrel 40, an outer cover 44, a positioning flange 42 and a heat insulating member 43. The positioning flange 42, surrounding the lateral wall of the inner barrel 40, is provided with a plurality of positioning pieces 421 for supporting against the outer wall of the inner barrel 40. The heat insulating member 43 is of substantially annular shape and has its outer rim embedded in a substantially annular groove 441 molded on the inner wall of the outer cover 44. The heat insulating member 43 is therefore secured between the flange 42 and the inner wall of the outer cover 44. The heat insulating member 43, sandwiched by the inner barrel 40 and the outer cover 44, stops heat generated inside from being conducted toward the outer cover 44 and achieves effects of enhancing user's safety and protecting the outer cover from burning out.

The present invention is thus described, and it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 

1-5. (canceled)
 6. A heat insulating structure for a hot air blower, comprising: an inner barrel; an outer cover surrounding said inner barrel; a positioning flange extending outwardly from said inner barrel; and an annular heat insulating member having an outer rim being embedded in an annular groove molded on an inner wall of said outer cover, said heat insulating member being secured between said flange and said inner wall of said outer cover; wherein said flange is an isolated member and has a plurality of positioning pieces around an inner rim thereof for supporting an outer wall of said inner barrel so that said flange can be secured on said inner barrel; wherein said heat insulating member is made of heat insulating materials and has a substantially U-shaped cross-section that defines a groove around an inner rim thereof for housing said flange. 